This invention relates to the manufacture of polyisocyanurate foams, and is more particularly concerned with a method for the manufacture of foams that utilizes a very small amount of a metal catalyst and also uses an amine/quaternary ammonium borate ester blend as a polyol. Methods of manufacturing polyisocyanurate foams are well known in the art, and include the method described in U.S. Pat. No. 4,256,802, issued to Koehler et al on Mar. 17, 1981 (hereinafter referred to as "Koehler"). Koehler discloses polyol blends comprising from about 20% to about 85% by weight of the blend of an amine diol or mixture of amine diols selected from the formula: ##STR1## wherein R is an aliphatic radical having from 8 to 18 carbon atoms, inclusive, each R.sub.1 is independently selected from the group consisting of hydrogen or methyl, x and y each independently have an average value from about 4 to about 15 inclusive; and from about 15 percent to about 80 percent by weight of a primary hydroxyl polyol (II) characterized by a molecular weight of from about 60 to about 1000. Koehler asserts that the polyol blends described therein are miscible with fluorocarbon blowing agents and water and other adjuvants including trimerization catalysts, and that its blends are particularly useful in a process for the preparation of polyisocyanurate foams. Those foams are said to be characterized by high reaction exotherms, making them particularly suited to the preparation of polyisocyanurate foam laminates.
It is noted that the Koehler process for foam manufacture, in which the "B" side utilizes a fluorocarbon blowing agent and a polyol, and also requires a trimerization catalyst in an amount of from 2 to 20 percent by combined weight of the catalyst, fluorocarbon blowing agent, and polyol. Trimerization catalysts disclosed in Koehler include (1) a catalyst combination of alkali metal salts of an N-substituted amide, an alkali metal salt of an N-(2-hydroxyphenyl)methyl glycine and optionally a tertiary amine trimerization catalyst, and (2) the same catalyst as described hereinabove except the optional component is a hydroxyalkyltrialkylammonium carboxylate salt.
Certain quaternary ammonium carboxylate salts and even quaternary boron salts have been disclosed as trimerization catalysts in several prior art references (see U.S. Pat. Nos. 4,040,992, 4,186,255 and 4,151,334). These quaternary borate salts disclosed are compounds such as, for example, sodium phenyl triethanolamineborates, which all have sodium as the cationic portion of the molecule. Thus, all of these quaternary borate salts are alkali metal salts (see U.S. Pat. No. 4,151,334, column 2, lines 6-7), compounds that were previously known as trimerization catalysts.